The multimedia consumer electronics market is rapidly evolving with increasingly sophisticated audio/video products. Consumers are becoming accustomed to high definition video in their home entertainment centers as well as high end graphic capabilities on personal computers. Several audio/video interface standards have been developed to link a digital audio/video source, such as a set-top box, DVD player, audio/video receiver, digital camera, game console or personal computer with an audio/video rendering device such as a digital television, a high definition video display panel or computer monitor. Examples of digital video interface technology available for consumer electronics comprise High-Definition Multimedia Interface (HDMI), Display Port, Digital Video Interface (DVI) and Unified Display Interface (UDI) for example. These audio/video interfaces may each comprise unique physical interfaces and communication protocols.
The IEEE 802.3 standard defines the (Medium Access Control) MAC interface and physical layer (PHY) for Ethernet connections at 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps data rates. Data rates and/or link distances may be improved however with more sophisticated component technologies. In some cases, newer technologies may be incorporated to enhance the performance of legacy infrastructure. For example, laser diodes with narrower bandwidth such as distributed feedback (DFB) lasers may provide higher coupling efficiencies. Receiver sensitivity may be improved by utilizing avalanche photodiodes (APD) rather than P-intrinsic-N (PIN) diodes. Signal processing techniques such as clock recovery and pre-emphasis may extend optical link range. Moreover, high performance fiber properties may reduce impairments such as fiber attenuation, modal distortion and/or material dispersion that may limit the data rate and/or the distance that an optical signal can travel effectively.
As higher data rates are sought, Ethernet standards are developed to support higher transmission rates and/or greater transmission distances over fiber infrastructure. Accordingly, various IEEE 802.3 standards have been ratified for 10 Gigabit-per-second (Gbps) rates. 10GBASE-SR may support short distance links between 26 m and 82 m utilizing multimode fiber. However, link distances may vary according to the physical properties of the fiber medium utilized. For example 10GBASE-SR may achieve improved link distances up to 300 m when new 50 micron 2000 MHz·km multimode fiber is utilized. Notwithstanding, 10GBASE-LRM may support distances up to 208 m over legacy multimode fiber. Long range optical 10GBASE-LR and extended range optical 10GBASE-ER may support distances of 10 km and 40 km respectively over single mode fiber. In another IEEE 802.3 technology, 10GBASE-LX4 utilizes four separate laser sources each operating at 3.125 Gbps with coarse wavelength division multiplexing (CWDM) to achieve an aggregate 10 Gbps rate. In this regard, 10GBASE-LX4 may support link distances in the range of 240 m to 300 m over multimode fiber or 10 km over single mode fiber. Even greater speeds may be achieved as present efforts exist within IEEE working groups for increasing transmission rates to 40 Gbps and 100 Gbps over existing fiber. In addition, non-standard technologies such as 1000BASE-ZX supporting 70 km links and 10GBASE-ZR supporting 80 km links are in use. Furthermore, non-standard or intermediate data rates may be utilized to improve performance and/or create implantation efficiencies. For example, a 10 Gbps interface may be clocked at a lower rate such as 2.5 Gbps or 5 Gbps. In this regard, a greater distance may be reached without significant impairments to the optical signal. Alternatively, transmitter and/or receiver optical sub systems may be simplified due to the lower rate traffic also without significant impairments to the optical signal.
MAC layer processes may also enable higher transmission rates for audio and video data by addressing quality of service issues such as latency restrictions. For example, A/V Bridging (AVB) comprises a set of specifications, which define service classes (or AVB services) that enable the transport of audio/video (A/V) streams (and/or multimedia streams) across an AVB-enabled network (or AVB network) based on selected quality of service (QoS) descriptors. Specifications, which enable the definition of AVB service classes, include the following.
A specification, which enables a set of AVB-enabled devices (or AVB devices) within an AVB network to exchange timing information. The exchange of timing information enables the devices to synchronize timing to a common system clock, which may be provided by a selected one of the AVB devices within the AVB network.
A specification, which enables an AVB destination device to register a request for delivery of a specified AV stream from an AVB source device. In addition, an AVB source device may request reservation of network resource, which enables the transmission of a specified AV stream. The Stream Reservation Protocol (SRP) defined within the specification provides a mechanism by which the AVB source device may register the request to reserve resources within the AVB network (such as bandwidth) to enable the transmission of the specified AV stream. The Multiple Multicast Registration Protocol (MMRP) may enable an AVB destination device to register the request for delivery of a specified AV stream.
A specification, which defines procedures by which AV streams are transported across the AVB network. These procedures may include methods for the queuing and/or forwarding of the AV streams by individual AVB devices within the AVB network.
A typical AVB network comprises a set of AVB devices, which are collectively referred to as an AVB block. An AVB network may comprise wired or optical local area networks (LANs) and/or wireless LANs (WLANs), for example. Individual AVB devices within the AVB network may include AVB-enabled endpoint computing devices (such as laptop computers and WLAN stations), AVB-enabled switching devices (AV switches) within LANs and AVB-enabled access points (APs) within WLANs, for example. Within the AVB block, AV destination devices may request AV streams from AV source devices, which may be transported across the AVB network within specified latency target values as determined from the QoS descriptors associated with delivery of the AV stream.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.